High-frequency translating circuits



Dec. 19, 1922. 1,438,988. L. ESPENSEHIED ET AL.

HIGH FREQUENCY TRANSLATING CIRCUITS.

ORIGINAL FILED SEPT-30,19I9.

dIIi 2 I is meant any Patented Dec. 19, 1922 LLOYD ESPJENSCHIED. 0FQUEENS, AND HERMAN A. AFFEL, 0F BROOKLYN, NEW YORK, v 'ASSIGNOES TOAMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORA- TION OE NEW YORK.

HIGH-FREQUENCY TRANSLATING CIRCUITS.

original application filed September 30, 1919, Serial No. 327,399.Divided and this application filed may To all whom it may concern:

Be it known that we, LLOYD Esrnnsomnn. and HERMAN A. AFFEL, residing atQueens and Brooklyn, in the counties of Queens and Kings and State ofNew York, respectivel have invented certain Improvements in Bigh-Frequency Translatmg C rcuits, of which the following is aspeclficatlon.

This invention relates to'high frequency translating circuits, and moreparticularly to arrangements for modulating currents of variousfrequencies. v p

This application 1s a d1v1s1on of our ooending application, Serial No.527,399, filed September 80, 1919, entltled High frequency translatingcircults.

As is well known, modulation of a plurality of frequencies consists 1nthe superposition of the input currents upon each other, either in themodulator element, or at some point in the input side of the saidelement. By the term modulator element ortion of an electrical circuit,the electrical constants ofwhich may be varied in accordance with slgnalvariations; thus, it maybe a vacuum tube 1n which the output resistance1s varied in accordance with grid potential, or an electric arc, theresistance of which is a funct on of the-impressed voltage, or, it maybe a reactance element such as an lnductance, the efiective permeabilityof which is varied by a controlling circuit, or a condenser, thecapacity of which may be controlled by variation in the plate separationor 1n the d1- electric constant. 0

It is desirable, therefore, to provide means for superposing the twoinput currents so as to avoid loss of energy and diminution ofmodulating efficiency arising from mutual shunting efi'ects. There are,in general, two ways whereby the input currents may be superposed so asto be rendered mutually non-interfering, one known as the method ofbalance and the other as the method of frequency selection; It is theobject of this invention to show means for superposing the inputcircuits upon each other by the method of frequency selection,

Serial Ito. 170,584.

a magnetic translating device such as a magnetic modulator.

Thls invention will be better'understood from the following descriptionread in connection with the attached drawing of which F1gure 1 shows aform of invention embodymg the principle of selectivity alone and Flgure2 shows the combination of selectivity and balance to prevent mutualinterference between the respective input circuits of the commonmodulating device.

Figure 1 shows a way in which the method of frequency selection may beapplied to a magnetic translating circuit. T, represents a source of lowfrequency signallng currents connected with an amplifier A, whereby theamplified currents will pass through the low passfilter F, and beimpressed upon the iron core modulating device M, by means of thewinding 1. High frequency oscillations from the source G, which, may beof any well-known type of generating device, may be impressed upon theamplifierA and the amplified currents passing through the high passfilter 'F will be impressed upon the modulator M, by means of thewinding 2'. The third winding 3 of the modulator is connected with asource of current B, by means of which the proper degree of saturationof the iron core of the modulator M, may be maintained, and a filter F 3is inserted between.

the source and the winding 3 to prevent shunting the low frequency voicecurrents and also the high frequency carrier current. A fourth winding 4is connected with a tuned output circuit coupled with the antenna X. Inthe operation of this circuit, low frequency signaling currents set upby T, are amplified by the amplifier A, and pass through the lowfrequency filter F, to

the modulator S-imultaneousl high frequency carrier currents produc by Gand amplified by A pass through the high frequency filter F and arelikewise 1mpressed upon the modulator M It will be seen that highfrequency osclllatlons cannot pass through the low passfilter F the lowfrequency circuit, and slmilarl low frequency currents cannot passthroug the high pass filter F to the hlgh frequency genera-ting circuit.In this manner interference between the input circuits is avoided, andthe modulated oscillations are transmitted by the winding 4 to theantenna circuit X. p L

Figure 2 shows an arrangement in which the principles of selectivity andof balance are combined for preventing interference between the inputcircuits of a magnetic modulatiiig device. The low frequency c1rcu1t hastherein a transmitter T and a low pass '1 filter F The low frequencysignals set u 1 high in this circuit are impressed across the win ing 1upon the central arm of the core of the modulator M High frequencyoscillations from the generator G pass through the ass filter-F andareimpressed upon the winding 2 upon one of the side arms of the core ofthemodulator M symmetrically arranged upon the same core is a winding 3which. is connected with the output ClICIllt: L Low frequency currentsimpressed upon winding 1 set up therein, a flux which divides in the armof the core upon which the winding 2 is placed, half of the flux passingup- Ward and half downward, which creates a neutral condition preventinginduction of currents in the winding 2 upon this core. In a similarmannervthe flux set up by. the high frequency winding 2 will not inducehigh frequency oscillations in the low frequency circuit. Filters F andF interposed in the low frequency and high frequency input circuitsrespectively prevent the passage of high frequency and low frequencycurrents through filters F and F respectively. If lowfrequency signalingcurrents are impressed upon the winding '1 upon the central arm of thecore, the resulting fluz: will change the permeability of the core withrespect to the winding 2. The high frequency current set up in, thewinding 2 by means of the source G will be modulated accordingly, andthe modulated high frequency current will be impressed-upon the winding3 of the output circuit L This arrangement shows means for combiningfrequency selective devices with a balanced iron core modulator, therebyassuring a higher degree of freedom from interference of theoscillations in one of the input circuits bythose in the other inputcircuit.

The circuit arrangements shown in the drawing are not limited to aparticular type of output circuit, such as aradio antenna or a metallictransmission line, but either arrangeme'nt is equally well adapted to beused with either type of output circuit. Although this invention hasbeen shown as embodied in a particular form, it is to be understood thatit is not so limited, but is capable of embodiment inother forms Withoutdepartin from the spirit and scope of the appended claims. 4

v What is claimed is:

1. In a hi h frequencysignaling system, the combination of a balancediron core modulating device, input circuits adapted to impress carriercurrent andsignaling current upon said translating circuit and frequencyselecting means associated with each input circuit to exclude from eachrespective circuit currents having frequencies different from that ofsaid circuit.

2. In a high frequency signaling system, the combination of a magnetictranslating device of a plurality of input circuits, each having asource of current of a definite frequency, and also a selective networkadapted to transmit that frequency of the particular source with whichthe said network is associated.

3. Ina high frequency signaling system,-

connected with a third winding and having selecting means connectedbetween said winding and said source, and anoutput circuit connectedwith a fourth winding 4. In a high frequency signaling system. thecombination of an antenna of a magnetic modulator having a plurality ofinput circuits, each characterized by a source of current of definitefrequency, and a filter adapted to transmit readily current of thatparticular frequency. 4

5. In a high frequency signaling the combination of an antenna 0 amagnetic translating device comprising a plural-- ity of input circuits,each characterized by a system,

source of current of a definite frequency, and

a filter adapted to transmit the said fre-.

quency.

6'. In a high frequency signaling system, the combination of a transmtting, circuit of a magnetic modulator having input circuits so arrangedas to prevent undesired induction of current from one input circuit intoanother input circuit, .each of the said input circuits beingcharacterized by a source of naeaeee current of a definite frequenc andby a filter adapted to transmit the irrequency of its respectivecircuit.

7. In a high frequency signaling system, the combination of a magneticmodulator having a plurality of windings, an output circuit, a pluralityof input circuits, each characterized by a source of current of definitefrequency, and a filter to transmit the said frequency, the saidcircuits being rendered mutually non-interfering by means of theirconnections With the windings of the said magnetic modulator.

In testimony whereof, I have signed my name to this specification this13th day of 15 May, 1921.

LLOYD ESPENSCHIED.

. In-testimony whereof, I have signed m

